Utilization of Raw Gypsum as Hydrated Filler in Bagasse Particleboard Bonded with a Formaldehyde-Free Epoxidized Natural Rubber Adhesive

Abstract

The present study described the feasibility of using raw gypsum as filler to improve the flame retardant and mechanical properties of particleboard (PB) prepared from bagasse. The PB was made with a formaldehyde-free adhesive based on epoxidized natural rubber (ENR) latex via a hot pressing process. The effect of gypsum loading on the mechanical properties of the PB was initially investigated. Both the tensile strength and modulus of rupture (MOR) of the PB tended to increase with increasing gypsum loading and reached the maximum values at 150 phr. The incorporation of gypsum into the PB beyond this loading level brought about a decrease in the corresponding properties. A horizontal burning test was conducted to determine the flame retardant properties of the PB (i.e., elapsed time and burning rate). The PB containing 150 phr of gypsum (PB-150G) was found to have a much shorter elapsed time and a lower burning rate than the PB with no gypsum added. The lower values of the corresponding properties indicated the better flame retardancy of PB. It was also found that the PB-150G exhibited a comparable level of flame retardancy to the PB containing 8 wt% of total flame retardants (i.e., 5 wt% magnesium chloride in combination with 3 wt% antimony trioxide) based on the combined weight of bagasse and ENR contained in the PB. These results revealed that the use of an appropriate amount of gypsum as filler could significantly enhance the flame retardancy with considerable improvement in the mechanical properties of BP.